1. Field of the Invention
The present invention relates to an optical communication system, an optical reader, and a method of reading information. The present invention is preferably applied to reading of identification information from compact wireless IC chips.
2. Description of the Related Art
Recently, radio frequency identification (RFID) has gained attention as a technology of identifying or managing articles, with which barcodes are replaced.
In RFID, identification information specific to articles is stored in a compact wireless device called a wireless IC tag (or wireless IC chip) and the articles are identified or managed on the basis of the identification information.
Various readers for reading identification information from wireless IC tags or wireless signals transmitted from wireless IC tags have been proposed. Some readers perform optical communication with wireless IC tags to transmit and receive identification information (for example, Japanese Unexamined Patent Application Publication No. 2006-11948).
In the technology disclosed in Japanese Unexamined Patent Application Publication No. 2006-11948, each optical reader includes an optical reader unit that emits a light beam to each optical ID tag and receives an optical signal reflected from the optical ID tag to read out identification information specific to the optical ID tag.
The optical ID tag includes a memory in which the specific identification information is stored, an optical converter that modulates the light beam emitted from the optical reader in accordance with the identification information stored in the memory to convert the modulated light beam into an optical signal, and a light reflector that reflects the light signal after the modulation in the incident direction of the light beam.
With the technology disclosed in Japanese Unexamined Patent Application Publication No. 2006-11948, the multiple optical ID tags that are arranged in proximity to each other in a space can be identified from remote locations, so that the optical readers can be used in the same manner as remote controllers to read the identification information concerning the optical ID tags.